tag:blogger.com,1999:blog-2821760991275369602.post4083887392989420045..comments2009-11-24T13:19:15.289-06:00Comments on Belgium Knee Warmers™: How High?Radio Freddyhttp://www.blogger.com/profile/07419506761098758178noreply@blogger.comBlogger35125tag:blogger.com,1999:blog-2821760991275369602.post-73367846204217909852007-12-31T19:15:00.000-06:002007-12-31T19:15:00.000-06:00This comment has been removed by the author.Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-61998656439731070132007-12-31T18:21:00.000-06:002007-12-31T18:21:00.000-06:001. We'll all let Freddy go ahead and make one. Let...1. We'll all let Freddy go ahead and make one. Let the creativity flow. <BR/><BR/>2. "The answer is simple: Make it easier to lean the bike over to carve a tight turn. Okay, so how do you do that? Simple. Lower the bottom bracket. Drop the center of gravity of the bicycle and leaning the bicycle into a turn becomes a good bit easier" . <BR/><BR/>Freddy, I'll be glad if you pointed out any sources of this information. True it happens in motorcycles (contrary to popular beliefs, some motorbikes are built with a higher engine position and higher CG for better leaning. Who do you believe?), but for a cyclocross application, with speeds much much lesser than those reached by motorbikes, I'll be very surprised to see if a cm or even two of BB drop will every do anything to leaning that is noticeable.<BR/><BR/>3. What leaning depends on more is the coefficient of friction of the ground, and the turning radius. Those two factors seem to overwhelm any other minute details.<BR/><BR/>4. Its also nice to keep the hands on the hoods while turning, that'll probably centralize CG (if you're worried about it) instead of it being more towards the rear. It could result in a stable turn.<BR/><BR/>My two cents.Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-59853955851641980302007-12-31T17:00:00.000-06:002007-12-31T17:00:00.000-06:00to get to the bottom of the BB height debate for c...to get to the bottom of the BB height debate for cross bikes you need to go back to the roots of the sport. Most cross bikes are still roughley based on the old Alan geometry that was unchanged for years. in those years they used toeclips, and needed to keep them out of the mud, and THAT was the main factor for the raising of the BB. As well as that they were using 28c tires back then. Now we all know that bike makers will listen to their PRO riders in regard to changes in geometry, but when a rider has been winning on the same bike for years the last thing they want is to change it. you can get used to anything, but it takes time to learn(or unlearn) a bike's handling style. <BR/>As for digging in a pedal once in a while I would contend that if you are pushing hard enough you SHOULD tap the pedal into the ground now and then. The best crit racers in the country do. Next time you are at a PRO crit take a look at some of the top guy's pedals, unless they just replaced them they will have scuff marks from hitting the ground while pedaling through corners.<BR/> these days though, with no toeclips(thank god) and 32 and 34c tires, I want my BB low as hell.<BR/> I really want to hear more about trail thoughgatodiablonoreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-76417871377310141302007-12-29T19:34:00.000-06:002007-12-29T19:34:00.000-06:00Art at 10:46,I can understand the difference a rec...Art at 10:46,<BR/><BR/>I can understand the difference a recumbent can make to CG. The rider is essentially almost lying close to the ground. But that is one end of the extreme.<BR/><BR/>At the moment, we do not have any objective tests done to show that a negligible movement of CG drop will make such an impact on cornering. So all other conclusions are just rider based preferences.Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-73255150530578272472007-12-29T19:23:00.000-06:002007-12-29T19:23:00.000-06:00This comment has been removed by the author.Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-63886908149268149832007-12-29T16:57:00.000-06:002007-12-29T16:57:00.000-06:00Of course you could always just run longer cranks ...Of course you could always just run longer cranks (180s) like some of us tall freaks do....<BR/><BR/>sure it is only a 5mm departure lower for me...<BR/><BR/>(from those on the same bike with 175 vs 180s)<BR/><BR/>Handle bar height also affects CG as it determines where the stuff above your hips is relative to the ground.gewillihttp://www.blogger.com/profile/17245908398787098575noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-762079953921880912007-12-29T10:46:00.000-06:002007-12-29T10:46:00.000-06:00Anonymous 2:32: There is a valid connection betwe...Anonymous 2:32: There is a valid connection between bb height and cg. If the bb gets raised or lowered, the saddle needs to move the same amount. Compact geometry on the other hand really doesn't have an effect. A top tube only weighs about 250g, compared to at least 79,000 grams for the rest of the bike + rider. Switching to a compact frame (moving the center of the top tube down 5cm) only moves the effective cg 0.15mm.Arthttp://www.blogger.com/profile/16355078079362433260noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-40499139275222578112007-12-29T02:32:00.000-06:002007-12-29T02:32:00.000-06:00If only the rider's weight was in the bottom brack...If only the rider's weight was in the bottom bracket. Instead it is about 60cm higher than that, where the saddle is located. BB height has little to do with center of gravity. However, a higher bottom gives greater clearance and a stiffer BB (shorter chainstays).<BR/><BR/>A bicycle is not a car - different physics, different solutions.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-82451097251637667202007-12-28T13:59:00.000-06:002007-12-28T13:59:00.000-06:00how long we gonna have to wait for you to get over...how long we gonna have to wait for you to get over the man-love of VDB and get back to this cross bike stuff ;)<BR/><BR/>yeah...<BR/><BR/>how the hell are those big giant guys staying on the wheels of the little tiny folks????gewillihttp://www.blogger.com/profile/17245908398787098575noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-6932564429188996502007-12-27T18:42:00.000-06:002007-12-27T18:42:00.000-06:00Another question I had :Center of gravity is dicta...Another question I had :<BR/><BR/>Center of gravity is dictated by mass. So CG of the combined rider-bike system must be closer to the rider (just simple physics). <BR/><BR/>Then wouldn't it suffice to say that a change in the rider will affect CG more than any drop in BB that say,you're resorting to doing?<BR/><BR/>I may be wrong, but someone should prove it . :)<BR/><BR/>Sorry about all this excitement in my brain neurons, but your post has got me thinking.Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-12879289436902333552007-12-27T18:09:00.000-06:002007-12-27T18:09:00.000-06:00Freddy,Since you brought up CG, I have a trick que...Freddy,<BR/><BR/>Since you brought up CG, I have a trick questions for you :)<BR/><BR/>1. If I put a 6 feet 5 rider (someone slightly taller than Hincapie maybe), would he corner slower than say, Robbie Mcewen, provided rest all factors are equal?<BR/><BR/>The CG argument must have it that the latter will be better, no?<BR/><BR/>Boy, but I believe Hincapie is one of the best descenders ever! He makes poetry out of it.<BR/><BR/>One can generalize the above question and think about it practically.Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-23809762697705548122007-12-27T18:08:00.000-06:002007-12-27T18:08:00.000-06:00This comment has been removed by the author.Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-18306265319067294762007-12-27T17:58:00.000-06:002007-12-27T17:58:00.000-06:001. As much as the temptation appears, I would refr...1. As much as the temptation appears, I would refrain from using multi-track analogies for single track vehicles. Not a bad observation though.Single track vehicles such as bicycles or motorcycles lean into a turn to counter centrifugal forces, while multi-track vehicles corner flat or roll slightly out of the turn with significant load transfers to the outside wheels.<BR/><BR/>The dynamics are different.<BR/><BR/>2. Nice thoughts to a better cross bike. Such a bike could also be ridden on road. Why make a separate bike for everything right? Its easy for companies to cash in on this aspect.<BR/><BR/>3. Your idea seems to be prior knowledge to some good framebuilders. For example, Waterford makes/used to make cyclocross bikes with low BB drop. Not sure if they still do, but you might want to check.<BR/><BR/>4. Since I like to be very analytical in nature, no peer reviewed literature has talked about the greatest effect on CG on a bicycle. I mean, why does everyone think BB drop makes the most difference? I'd like someone to quantify the % drop in CG with, say, a cm of BB drop. And how is a compact geometry to lower CG compared with BB drop (assuming the compact bike will be made decent enough to shoulder)?<BR/><BR/>5. A good design in this area will think about proper trail, wheelbase, stability and stand over height.<BR/><BR/>6. If you don't want to worry about all these, I would just plead with the course designers to make more forgiving turns. Lol...Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-5093512584933743732007-12-27T17:47:00.000-06:002007-12-27T17:47:00.000-06:00This comment has been removed by the author.Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-8661422397891255402007-12-27T17:39:00.000-06:002007-12-27T17:39:00.000-06:00This comment has been removed by the author.Ronhttp://www.blogger.com/profile/18394865788996482667noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-90970580248635859562007-12-27T08:33:00.000-06:002007-12-27T08:33:00.000-06:00The history of building bicycles and parts has alw...The history of building bicycles and parts has always shifted one direction to the other and then back again. It's a "cycle". Higher, lower, steeper, more or less are always "better" until it's the norm and then suddenly an old idea becomes better again.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-74157016222735022302007-12-24T14:09:00.000-06:002007-12-24T14:09:00.000-06:00I can still hit my high side pedal on some of the ...I can still hit my high side pedal on some of the off cambers they throw at us in New England, especially when the grass is clumpy. So there is such a thing as too low.<BR/><BR/>I'm not sure how these really big guys get their long wheelbase bikes to turn well though. But they do... talent maybe?solobreakhttp://www.blogger.com/profile/08417776456965743082noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-10243752595569781592007-12-23T20:34:00.000-06:002007-12-23T20:34:00.000-06:00retro grouch, just curious...have you tried them s...retro grouch, just curious...have you tried them side by side? I have, on the same courses even... the larger bb drop trumped the 'pedalling through corners' everytime. I rode a 55mm bb drop for 5 years. It only took me a few races to see the 70mm bb drop was the clear winner. Oh yes...same fork rake on both bikes and nearly the same front end geo. 72.7 vs 72.5.tjhhttp://www.blogger.com/profile/12168109347759222839noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-67032572090414876532007-12-23T14:12:00.000-06:002007-12-23T14:12:00.000-06:00I'll measure my frame geometry and let you guys kn...I'll measure my frame geometry and let you guys know...not that you asked, but my Bonty 'Cross is one of the best handling bikes I've ever ridden...here's some pix...<BR/><BR/>http://sportinglifesociety.com/<BR/><BR/>click the link for more..<BR/><BR/>p.s. not a cheap ploy to get you to my site...The Sporting Life Societyhttp://www.blogger.com/profile/15258218395931121058noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-83091431120527364012007-12-23T10:17:00.000-06:002007-12-23T10:17:00.000-06:00The mini cooper analogy isn't entirely correct. O...The mini cooper analogy isn't entirely correct. On a car, it isn't the cg height that matters so much as the cg relative to track width. All else being equal, lowering the cg on a bike does nothing to the lean angle. Whether leaning on a taller bike feels like being on stilts or not depends entirely on the front end geometry.Arthttp://www.blogger.com/profile/16355078079362433260noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-11686370541156521502007-12-22T20:39:00.000-06:002007-12-22T20:39:00.000-06:00Sorry, I meant the wheel's radius.Sorry, I meant the wheel's radius.Hup Unitedhttp://www.blogger.com/profile/13202422582287543518noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-69058466962149508682007-12-22T20:34:00.000-06:002007-12-22T20:34:00.000-06:00Higher BB allows you to peddle through the corners...Higher BB allows you to peddle through the corners allowing you to keep the momentum high.This was proven on crit bike and mountain bikes (when the races had actual single track)The ability to peddle in a corner can be a huge advantage higher lean angle are a good side effect too as they can block out more space.<BR/><BR/>BTW the use of a scientific (atmo) term is not cool if you don't know what it is.Retro grouchhttp://www.blogger.com/profile/10433021964493915460noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-59527470740736722882007-12-22T13:24:00.000-06:002007-12-22T13:24:00.000-06:00What no one has mentioned.....which I think is wor...What no one has mentioned.....which I think is worth mentioning.....is the fact that BB drop, when comparing from bike to bike, is the same no matter the tire radius. <BR/><BR/>BB height, however, changes drastically with tire choice. (And therefore center of gravity) And we know how many cross tyres are out there. Look at the review CN did on Wellens' bike. The dude is running like 32mm slicks!!!!! When he puts his "mud" tyres on, I'm sure his BB height is jacked by at least 1 cm. <BR/><BR/>And...once BB height changes, let's say it's getting higher off the ground for this example, that "raises the bar" of how high one needs to jump to get back on the bike. The saddle height from BB center to top of saddle remains the same from a 5.8 cm BB drop to a 7.0 BB drop. <BR/><BR/>ATMO has spoken in the last post.Hup Unitedhttp://www.blogger.com/profile/13202422582287543518noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-39095697673094740072007-12-21T21:22:00.000-06:002007-12-21T21:22:00.000-06:00Padraig wrote: "The answer is simple: Make it easi...Padraig wrote:<BR/><A> "The answer is simple: Make it easier to lean the bike over to carve a tight turn. Okay, so how do you do that? Simple. Lower the bottom bracket. Drop the center of gravity of the bicycle and leaning the bicycle into a turn becomes a good bit easier."</A> <BR/><BR/><I>gets it</I> atmo.e-RICHIEhttp://www.blogger.com/profile/13004654079480170475noreply@blogger.comtag:blogger.com,1999:blog-2821760991275369602.post-57065363154713205102007-12-21T17:17:00.001-06:002007-12-21T17:17:00.001-06:00I tried to tell this to the design gurus at C'dale...I tried to tell this to the design gurus at C'dale 5 years ago...they gave me the 1,000 yard stare. Then Tim Jiohnson siad lower the BB and they thought they had heard the voice of God. Check the bb height on their bikes.Flathead Frednoreply@blogger.com